Heat transfer circuit with flow dependent heat exchanger

ABSTRACT

A heat transfer circuit includes a compressor, a heat exchanger, an expander, a plurality of valves, and a working fluid. The heat exchanger including a plurality of coils and is configured to exchange heat between the working fluid and a process fluid. The working fluid flows through the first heat exchanger in a first direction by flowing through the plurality of coils in series and in a second direction by flowing through the plurality of coils in parallel. A method of operating a heat transfer circuit includes operating in a first mode and operating in a second mode. In the first mode, working fluid flows though coils of a heat exchanger in series. In a second mode, the working fluid flows through the coils of the heat exchanger in parallel.

FIELD

This disclosure relates to heat transfer circuits used in heating, ventilation, air conditioning, and refrigeration (HVACR) systems. More specifically, this disclosure relates to heat exchangers in heat transfer circuits.

BACKGROUND

HVACR systems are generally used to heat, cool, and/or ventilate an enclosed space (e.g., an interior space of a commercial building or a residential building, an interior space of a refrigerated transport unit, or the like). A HVACR system may include a heat transfer circuit that utilizes a working fluid to provide cooled or heated air to an area. The HVACR system can include a first heat exchanger and a second heat exchanger. A process fluid flows through the first heat exchanger and is heated or cooled by the working fluid. The heated or cooled process fluid is then utilized to heat or cool the enclosed space. A different process fluid can flow through the second heat exchanger and heat and/or cool the working fluid. The heat transfer circuit can be configured to operate in multiple modes. A flow direction of the working fluid through each heat exchanger can change based on the mode of the heat transfer circuit.

SUMMARY

A heating, ventilation, air conditioning, and refrigeration (HVACR) system can include a heat transfer circuit configured to heat and/or cool a process fluid (e.g., air, water and/or glycol, or the like). A working fluid is circulated through the heat transfer circuit. A different process fluid is used to remove and/or supply heat to the working fluid. The heat transfer circuit includes a compressor to compress the working fluid and an expander to expand the working fluid.

In an embodiment, the heat transfer circuit includes a first heat exchanger, a second heat exchanger, and a plurality of valves. The first heat exchanger is configured to exchange heat between the working fluid and a first process fluid. The first heat exchanger includes a plurality of heat exchange coils. The working fluid flows through the heat exchange coils of the first heat exchanger. The first process fluid flows through the heat exchange coils of the first heat exchanger in parallel, separate from the working fluid.

The valves are configured to direct the working fluid through the heat exchange coils of the first heat exchanger based on a flow direction of the working fluid through the first heat exchanger. When the working fluid flows through the first heat exchanger in a first direction, the working fluid flows through its heat exchange coils in series. When the working fluid flows through the first heat exchanger in a second direction, the working fluid flows through its heat exchange coils in parallel.

In an embodiment, the second direction is opposite of the first direction.

In an embodiment, the heat transfer circuit is configured to operate in at least a first mode and a second mode. In an embodiment, the working fluid flows through the first heat exchanger is the first direction when in the first mode and flows through the first heat exchanger in the second direction in the second mode.

In an embodiment, the first mode is a cooling mode and the second mode is a heat pump mode.

In an embodiment, a second process fluid flows through the second heat exchanger, separate from the working fluid. The second process fluid is the process fluid to be heated and/or cooled by heat transfer circuit. The heat transfer circuit is configured to cool the second process fluid with the working fluid in the cooling mode and to heat the second process fluid with the working fluid in the heat pump mode.

In an embodiment, the first process fluid is the different process fluid. The different process fluid is heated in the cooling mode and cooled in the heat pump mode by the working fluid.

In an embodiment, the plurality of valves includes two or more check valves. In an embodiment, the plurality of valves includes a three-way valve.

In an embodiment, the plurality of valves includes a control valve.

In an embodiment, the heat transfer circuit includes a controller that controls the control valve.

In an embodiment, the heat transfer circuit includes a reversing valve. The reversing valve configured to change the flow direction of the working fluid through the first heat exchanger.

In an embodiment, a method of operating a heat transfer circuit includes operating in a first mode and operating in second mode. In the first mode, working fluid is compressed in a compressor and directed through a first heat exchanger in a first direction. The first heat exchanger includes a plurality of heat exchange coils. The working fluid flows through the first heat exchanger in the first direction by flowing through the heat exchange coils in series. In the second mode, the working fluid is directed through the first heat exchanger in a second direction. The working fluid flows through the first heat exchanger in the second direction by flowing through the heat exchange coils of the first heat exchanger in parallel.

BRIEF DESCRIPTION OF THE DRAWINGS

Both described and other features, aspects, and advantages of a heat transfer circuit and methods of operating a heat transfer circuit will be better understood with the following drawings:

FIG. 1 is a schematic diagram of an embodiment of a heat transfer circuit.

FIG. 2A is a schematic diagram of the heat transfer circuit in FIG. 1 in a cooling mode, according to an embodiment.

FIG. 2B is a schematic diagram of the heat transfer circuit in FIG. 1 in a heat pump mode, according to an embodiment.

FIG. 3 is a schematic diagram of an embodiment of a heat transfer circuit.

FIG. 4A is a schematic diagram of the heat transfer circuit in FIG. 3 in a cooling mode, according to an embodiment.

FIG. 4B is a schematic diagram of the heat transfer circuit in FIG. 3 in a heat pump mode, according to an embodiment.

FIG. 5 is a schematic diagram of an embodiment of a heat transfer circuit.

FIG. 6A is a schematic diagram of the heat transfer circuit in FIG. 5 in a cooling mode, according to an embodiment.

FIG. 6B is a schematic diagram of the heat transfer circuit in FIG. 5 in a heat pump mode, according to an embodiment.

FIG. 7 is a schematic diagram of an embodiment of a heat transfer circuit.

FIG. 8A is a schematic diagram of the heat transfer circuit in FIG. 7 in a cooling mode, according to an embodiment.

FIG. 8B is a schematic diagram of the heat transfer circuit in FIG. 7 in a heat pump mode, according to an embodiment.

FIG. 9 is a schematic diagram of an embodiment of a heat transfer circuit.

FIG. 10A is a schematic diagram of the heat transfer circuit in FIG. 9 in a cooling mode, according to an embodiment.

FIG. 10B is a schematic diagram of the heat transfer circuit in FIG. 9 in a heat pump mode, according to an embodiment.

FIG. 11 is a block diagram of an embodiment of a method of operating a heat transfer circuit.

Like reference characters refer to similar features.

DETAILED DESCRIPTION

A heating, ventilation, air conditioning, and refrigeration system (“HVACR”) is generally configured to heat and/or cool an enclosed space (e.g., an interior space of a commercial building or a residential building, an interior space of a refrigerated transport unit, or the like). The HVACR system includes a heat transfer circuit to heat or cool a first process fluid (e.g., air, water and/or glycol, or the like). A working fluid flows through the heat transfer circuit and heats and/or cools the first process fluid. The heat transfer circuit can be configured to have multiple modes. The heat transfer circuit in a cooling mode cools the first process fluid and in a heat pump mode heats the first process fluid. The first process fluid may heat and/or cool the enclosed space directly or indirectly. For example, indirect heating and/or cooling may include working fluid heating and/or cooling the first process fluid, and the cooled/heated first process heating an intermediate fluid (e.g., air, water and/or glycol, or the like) that heats and/or cools the enclosed space.

A second process fluid (e.g., air, water and/or glycol, or the like) can be used to remove and/or supply heat from/to the heat transfer circuit. The second process fluid absorbs heat from and/or provides heat to the working fluid. The second process fluid may cool the working fluid in the cooling mode and heat the working fluid in the heat pump mode.

The heat transfer circuit includes a heat exchanger that has a plurality of heat exchange coils. The working fluid flows through the heat exchanger. The first process fluid or the second process fluid also flows through the heat exchanger separately from the working fluid. The working fluid and the first/second process fluid flows through each coil in the heat exchanger. The working fluid flows through the heat exchanger in different directions when operating in a cooling mode and in a heat pump mode.

When operating in one mode, the working fluid flows through the heat exchanger in one direction and can operate as a condenser for the working fluid. When operating in a different mode, working fluid flows through the heat exchanger in a different direction and can operate as an evaporator for the working fluid.

Previously, the working fluid flowed through the heat exchange coil(s) in the same manner, except in an opposite direction. This may cause the heat exchanger to have non-ideal pressure drop(s) when operating as a condenser or as an evaporator, or this may cause the heat exchanger to have a non-ideal pressure drop for both operations. The non-ideal pressure drop(s) cause the heat exchanger to operate less efficiently in at least one mode. In contrast, an ideal pressure drop allows the heat exchanger to operate more efficiently. For example, the heat exchanger had an ideal pressure drop when operating as the condenser but a non-ideal pressure drop when operating as an evaporator. For example, the heat exchanger had a non-ideal pressure drop as an evaporator and a non-ideal pressure drop as a condenser, but the amount each pressure drop varies from its ideal pressure drop can be minimized.

Embodiments disclosed are to a heat transfer circuit and methods of operating a heat transfer circuit that direct working fluid through the heat exchange coils of the heat exchanger differently based on its flow direction to have an ideal pressure drop in both flow directions.

FIG. 1 is a schematic diagram of an embodiment of a heat transfer circuit 1. In an embodiment, the heat transfer circuit 1 is utilized in a HVACR system. The heat transfer circuit 1 includes a compressor 10, a first heat exchanger 20, an expansion device 50, a second heat exchanger 60, a reversing valve 70, and a controller 90. In an embodiment, the heat transfer circuit 1 can be modified to include additional components, such as, for example, an economizer heat exchanger, one or more additional valve(s), sensor(s) (e.g., a flow sensor, a temperature sensor), a receiver tank, or the like.

The components of the heat transfer circuit 1 are fluidly connected. The heat transfer circuit 1 includes a reversible main flow path 5 for the working fluid. The reversing valve 70 controls the flow direction of the working fluid through the reversible main flow path 5. The reversible main flow path 5 extends from the reversing valve 70 through the first heat exchanger 20, the expansion device 50, the second heat exchanger 60, and back to the reversing valve 70. In an embodiment, the reversing valve 70 may be a 4-way valve. The reversing valve 70 in FIG. 1 is a single unit. However, the reversing valve 70 in an embodiment may be formed by a plurality of control valve(s).

Dotted lines are provided in the Figures to indicate fluid flows through some components (e.g., first heat exchanger 20, second heat exchanger 60) for clarity, and should be understood as not specifying a specific route in each component. Dashed dotted lines are provided in the Figures to illustrate electronic communications between different features. Dashed lines are provided to illustrate passageways that are blocked in a specific mode of the heat transfer circuit.

The compressor 10 includes a suction inlet 12 and a discharge outlet 14. Working fluid is suctioned through the suction inlet 12, compressed by the compressor 10, and then discharged as compressed working fluid from the discharge outlet 14. The reversing valve 70 is fluidly connected to the suction inlet 12 of the compressor 10, the discharge outlet 14 of the compressor 10, the first heat exchanger 20, and the second heat exchanger 60. The reversing valve 70 controls whether the compressed working fluid flows first from discharge outlet 14 to the first heat exchanger 20 or from the discharge outlet 14 to the second heat exchanger 60.

A first process fluid PF₁ flows through the first heat exchanger 20 separate from the working fluid. The first heat exchanger 20 allows the working fluid and the first process fluid PF₁ to be in a heat transfer relationship without physically mixing as they each flow through the first heat exchanger 20. As the working fluid and the first process fluid PF₁ flow through the first heat exchanger 20, the working fluid and the first process fluid PF₁ exchange heat which affects the temperatures of the working fluid and the first process fluid PF₁. In an embodiment, the first process fluid PF₁ may be air, water and/or glycol, or the like that is suitable for transfer heat to and/or away from the working fluid and the heat transfer circuit 1. For example, the first process fluid PF₁ may be ambient air from an outside atmosphere, water to be heated as hot water, or any suitable fluid for transferring heat from and/or to the heat transfer circuit 1. In an embodiment, the first heat exchanger 20 may be an outdoor heat exchanger.

A second process fluid PF₂ flows through the second heat exchanger 60 separately from the working fluid. The second heat exchanger 60 allows the working fluid and the second process fluid PF₂ to be in a heat transfer relationship within the second heat exchanger 60 without physically mixing. As the working fluid and the second process fluid PF₂ flow through the second heat exchanger 60, the working fluid and the second process fluid PF₂ exchange heat which affects the temperatures of the working fluid and the second process fluid PF₂. In an embodiment, the second process fluid PF₂ is air heated or cooled by the HVACR system and ventilated to the enclosed space to be conditioned. In an embodiment, the second process fluid PF₂ is an intermediate fluid (e.g., water and/or glycol, heat transfer fluid, or the like), and the heated or cooled second process fluid PF₂ is utilized by the HVACR system to heat or cool air ventilated to the enclosed space.

The expansion device 50 is located between the first heat exchanger 20 and the second heat exchanger 60 in the reversible main flow path 5. The working fluid flowing to the expansion device 50 is liquid or mostly liquid. The expansion device 50 allows the working fluid to expand. The expansion causes the working fluid to significantly decrease in temperature. In an embodiment, the working fluid is in a mixed phase after passing through the expansion device 50. The gaseous/liquid working fluid has a lower temperature after being expanded by the expansion device 50. An “expansion device” as described herein may also be referred to as an expander. In an embodiment, the expander 50 may be an expansion valve, an expansion plate, an expansion vessel, an orifice, or the like, or other such types of expansion mechanisms. It should be appreciated that the expander 50 may be any type of expander used in the field for expanding a working fluid to cause the working fluid to decrease in temperature.

In an embodiment, the heat transfer circuit 1 includes a first mode and a second mode. The heat transfer circuit 1 may be operated in a first mode or a second mode depending upon the desired heating/cooling for the second process fluid PF₂. The heat transfer circuit 1 is configured to change between the first mode and the second mode based on whether the second process fluid PF₂ is to be cooled or heated. For example, it might be desired for the heat transfer circuit 1 to heat the second process fluid PF₂ in conditions of colder temperatures (e.g., in the winter) and to cool the second process fluid PF₂ in conditions of warmer temperatures (e.g. in the summer). In an embodiment, the heat transfer circuit 1 changes between the first mode and the second mode by the reversible valve 70 changing the flow direction through the reversible main flow path 5.

In the first mode, the heat transfer circuit 1 operates as a cooling system (e.g., a fluid chiller of an HVACR system, an air conditioning system, or the like) that cools the second process fluid PF₂. In an embodiment, the first mode may be a cooling mode. In the cooling mode, the reversing valve 70 in a first position directs the compressed working fluid from the compressor 10 to the first heat exchanger 20. In the first position, the reversing valve 70 also directs the working fluid from the second heat exchanger 60 back to the compressor 10. The operation of the heat transfer circuit 1 in the cooling mode will be discussed in further detail below with respect to FIG. 2A.

In the second mode, the heat transfer circuit 1 operates as a heat pump system heats the second process fluid PF₂. In an embodiment, the second mode may be a heat pump mode. In the second mode, the reversing valve 70 in a second position directs the compressed working fluid from the compressor 10 to the second heat exchanger 60. In the second position, the reversing valve 70 also directs working fluid from the first heat exchanger back to the suction inlet 112 of the compressor 110. Operation of the heat exchanger circuit 1 in the heat pump mode will be discussed in further detail below with respect to FIG. 2B.

The heat exchanger 20 in FIG. 1 is shown as a single unit that includes the heat exchange coils 22A, 22B. However, the first heat exchanger 20 in an embodiment may include multiple separate units that each includes a heat exchange coil 22A, 22B and to which the first process fluid PF₁ is supplied in parallel.

In an embodiment, each heat exchange coil 22A, 22B includes passageways (not shown) through which the first process fluid PF₁ flows and different passageways (not shown) through which the working fluid flows. The working fluid and the first process fluid PF₁ can exchange heat through the material of the passageways. For example, in an embodiment of the heat exchange coil 22A, 22B, the working fluid might flow through tubes (not shown) and the first process fluid PF₁ might flow around the outsides of the tubes.

The working fluid flows through the heat exchange coils 22A, 22B differently based on a flow direction of the working fluid through the first heat exchanger 20. In an embodiment, the flow direction may be different between different modes of the heat transfer circuit 1. In an embodiment, the reversible main flow path 5 includes three branches 28A, 28B, 28C for directing the working fluid through the heat exchanger heat exchange coils 22A, 22B. In addition to the components discussed herein, the reversible main flow path 5 and its branches 28A, 28B, and 28C can be formed using one or more pipes. The reversible main flow path 5 splits into three branches 28A, 28B, 28C before the heat exchange coils 22A, 22B and the three branches 28A, 28B, and 28C converge after the heat exchange coils 22A, 22B. The three branches 28A, 28B, 28C diverge and converge between the reversing valve 70 and the expander 50. In an embodiment, the branches 28A, 28B, 28C, before converging, are also fluidly connected by the heat exchange coils 22A, 22B. In an embodiment, before converging, the first branch 28A and second branch 28B are fluidly connected by the second heat exchange coil 22B, and the second branch 28B and the third branch 28C are fluidly connected by the first heat exchange coil 22A. In an embodiment, the branches 28A, 28B, 28C do not include the heat exchange coils 22A, 22B.

In an embodiment, the heat transfer circuit includes valves 30, 32, 34, 36, 38, 40, 42 that are configured to direct the working fluid through the plurality of heat exchange coils 22A, 22B in parallel or series depending upon the flow direction of the working fluid through the first heat exchanger 20. In an embodiment, each of the branches 28A, 28B, 28C includes at least two of the valves 30, 32, 34, 36, 38, 40, 42. The working fluid flows through the plurality of heat exchange coils 22A, 22B in series when the heat transfer circuit 1 is operating in the cooling mode, and flows through the plurality of heat exchange coils 22A, 22B in parallel when the heat transfer circuit 1 is operating in the heat pump mode.

In an embodiment, the valves 30, 32, 34, 36, 38, 40, 42 are check valves. Check valves only allow fluid to flow through the valve in one direction. The check valves 30, 32, 34, 36, 38, 40, 42 passively direct the working fluid. The check valves 30, 32, 34, 36, 38, 40, 42 can provide the desired series/parallel routing of the working fluid through the heat exchange coils 22A, 22B without requiring additional active controls. In an embodiment, one or more of the valves 30, 32, 34, 36, 38, 40, 42 may be control valve(s), and a controller (e.g., the controller 90) may be configured to close or open the valve(s) to respectively block and/or allow working fluid as described below.

In an embodiment, the controller 90 controls the reversible valve 70. When a different mode for the heat transfer circuit 1 is desired, the controller 90 can change the position of the reversible valve 70. In an embodiment, the controller 90 may be the controller of the HVACR system. In an embodiment, the controller 90 includes memory (not shown) for storing information and a processor (not shown). The controller 90 in FIG. 1 and described below is described/shown as a single component. However, it should be appreciated that a “controller” as shown in the Figures and described herein may include multiple discrete or interconnected components that include a memory (not shown) and a processor (not shown) in an embodiment.

The heat exchanger 20 shown in FIG. 1 includes the two heat exchange coils 22A, 22A. However it should be understood that the heat exchanger 20 in an embodiment may have more than two heat exchange coils 22A, 22B. In such an embodiment, the heat transfer circuit 1 may include more valves 30, 32, 34, 36, 38, 40, 42 and branches 28A, 28B, 28C so that the working fluid is properly directed through each of the additional heat exchange coils in parallel/series as discussed herein.

FIG. 2A is a schematic diagram of the heat transfer circuit 1 when operating in the cooling mode. The flow path of the working fluid through the heat transfer circuit 1 is shown in bold lines. Dashed lines are illustrated in the reversible valve 70 for the flow paths that are closed. In the cooling mode, compressed working fluid flows from the discharge outlet 14 of the compressor 10 through the reversible valve 70 valve to the first heat exchanger 20, from the first heat exchanger to the expander 50, from the expander 50 to the second heat exchanger 60, and from the second heat exchanger 60 through the reversible valve 70 to the suction inlet 12 of the compressor 10. The working fluid flows from the reversible valve 70 through the first heat exchanger 20 in a first direction D₁ to the expander 50.

In the cooling mode, the first process fluid PF₁ flowing through the first heat exchanger 20 absorbs heat from the working fluid which cools the working fluid as it flows through the first heat exchanger 20. The first heat exchanger 20 in the cooling mode operates as a condenser that at least partially condenses the working fluid flowing through the first heat exchanger 20. The gaseous/liquid working fluid 20 is then expanded in the expander 50, which further cools the working fluid. The gaseous/liquid working fluid then passes through the second heat exchanger 60. The colder working fluid flowing through the second heat exchanger 60 absorbs heat from the second process fluid PF₂, which cools the second process fluid flowing through the second heat exchanger 60. The second heat exchanger 60 in the cooling mode operates as an evaporator that mostly or fully evaporates the working fluid flowing through the second heat exchanger 60.

In an embodiment, the valves 30, 32, 34, 36, 38, 40, 42 are configured so that the working fluid flowing through the first heat exchanger 20 in the first flow direction D₁ in the cooling mode flows through its heat exchange coils 22A, 22B in series. In an embodiment, the working fluid flows through the heat exchange coils 22A, 22B in series when the heat exchanger 20 is operating as a condenser. In an embodiment, the heat exchange coils series provide an ideal pressure drop for operating a condenser at a higher efficiency. The first heat exchanger 20 can advantageously have a higher efficiency in the cooling mode when operating as a condenser by the working fluid flowing through its heat exchange coils 22A, 22B in series.

In an embodiment, the working fluid passes through the first heat exchange coil 22A, passes through the second heat exchange coil 22B, and then flows to the expander 50. The first process fluid PF₁ flows through the heat exchange coils 22A, 22B in parallel. A portion of the first process fluid PF₁ flows through the first heat exchange coil 22A, and a different portion of the first process fluid PF₁ flows through the second heat exchange coil 22B.

In an embodiment, the valves 30, 32, 36, 40 prevent the working fluid from flowing through the heat exchange coils 22A, 22B in parallel or by-passing one or more of the heat exchange coils 22A, 22B. In an embodiment, seven valves 30, 32, 34, 36, 38, 40, 42 direct the working fluid through heat exchange coils 22A, 22B of the first heat exchanger 20. The valves 30, 32, 34, 36, 38, 40, 42 are each located between the reversing valve 70 and the expander 50. The working fluid flowing through the first heat exchanger 20 in the first direction flows through three of the valves 38, 40, 42 and four of the valves 30, 32, 34, 36 block working fluid.

As shown in FIG. 2A, a first valve 30, a second valve 32, a third valve 34, and a fourth valve 36 each block working fluid when the working fluid is flowing through the first heat exchanger 20 in the first direction D₁ in the cooling mode. The working fluid flows through a fifth valve 38, a sixth valve 40, and a seventh valve 42. In an embodiment, the first branch 28A includes the first valve 30 and the seventh valve 42; the second branch 28B includes the second valve 32, the third valve 34, and the sixth valve 40; and the third branch 28C includes the fourth valve 36 and the fifth valve 38.

The first valve 30 is between the reversing valve 70 and the second heat exchange coil 22B. The first valve 30 is also between the reversing valve 70 and the fifth valve 38. In the cooling mode, the first valve 30 connects upstream of the heat exchange coils 22A, 22B and connects downstream of the heat exchange coils 22A, 22B. In the cooling mode, the first valve 30 prevents the working fluid flowing from the reversing valve 70 from bypassing the heat exchange coils 22A, 22B.

The second valve 32 is between the reversing valve 70 and the first heat exchange coil 22A and between the reversing valve 70 and the second heat exchange coil 22B. The second valve 32 is also between the reversing valve 70 and the seventh valve 42. In the cooling mode, the second valve 32 connects upstream the heat exchange coils 22A, 22B and connects downstream of the first heat exchange coil 22A. In the cooling mode, the second valve 32 prevents the working fluid flowing from the reversing valve 70 from flowing to the second heat exchange coil 22B and bypassing the first heat exchange coil 22A.

The third valve 34 is between the second heat exchange coil 22B and the expander 50. The third valve 34 is also between the second valve 32 and the expander 50 and between the sixth valve 40 and the expander 50. In the cooling mode, the third valve 34 connects upstream of the second heat exchange coil 22B and downstream of the first heat exchange coil 22A and connects downstream of the second heat exchange coil 22B. In the cooling mode, the third valve prevents the working fluid after passing through the first heat exchange coil 22A from bypassing the second heat exchange coil 22B.

The fourth valve 36 is between the first heat exchange coil 22A and the expander 50. The fourth valve 36 is also between the fifth valve 38 and the expander 50. In the cooling mode, the fourth valve 36 connects upstream of the first heat exchange coil 22A and downstream of the second heat exchange coil 22B. In the cooling mode, the fourth vale 36 prevents the working fluid flowing from the reversing valve 70 from bypassing the heat exchange coils 22A, 22B.

The fifth valve 38 is between the reversing valve 70 and the first heat exchange coil 38. The fifth valve 38 is also between the reversing valve 70 and the fourth valve 36. In the cooling mode, the fifth valve 38 is upstream of the first heat exchange coil 22A and the working fluid flows through the fifth valve 38 before flowing through the heat exchange coils 22A, 22B.

The sixth valve 40 is between the first heat exchange coil 22A and the second heat exchange coil 22B. The sixth valve 40 is also between the second valve 32 and the third valve 34. In the cooling mode, the sixth valve 40 is downstream of the first heat exchange coil 22A and upstream of the second heat exchange coil 22B, and the working fluid flows through the fifth valve 38 after the first heat exchange coil 22A and before the second heat exchange coil 22B.

The seventh valve 42 is between the second heat exchange coil 22B and the expander 50. The seventh valve 42 is also between the first valve 30 and the expander 50. In the cooling mode, the seventh valve 42 is downstream of the second heat exchange coil 22B, and the working fluid flows through the seventh valve 42 after flowing through the first heat exchange coil 22A and the second heat exchange coil 22B.

FIG. 2B is a schematic diagram of the heat transfer circuit 1 when operating in the heat pump mode. The flow path of the working fluid through the heat transfer circuit 1 is shown in bold lines. Dashed lines are illustrated in the reversible valve 70 for the flow paths that are closed. Compressed working fluid flows from the discharge outlet 14 of the compressor 10 through the reversible valve 70 valve to the second heat exchanger 60, from the second heat exchanger 60 to the expander 50, from the expander 50 to the first heat exchanger 20, and from the first heat exchanger 20 through the reversible valve 70 to the suction inlet 12 of the compressor 10. The working fluid flows from the expander 50 through the first heat exchanger 20 in a second direction D₂ to the reversible valve 70.

In the heat pump mode, the second process fluid PF₂ flowing through the second heat exchanger 60 absorbs heat from the working fluid which cools the working fluid as it flows through the second heat exchanger 60. In an embodiment, the heated second process fluid PF₂ may be air that is then ventilated to an indoor space to heat the indoor space. In an embodiment, the heated second process fluid PF₂ may be a fluid (e.g, water and/or glycol, or the like) that is used to heat air that is then ventilated to an indoor space or is used to heat air in the indoor space. The second heat exchanger 60 in the heat pump mode operates as a condenser that at least partially condenses the working fluid flowing through the second heat exchanger 60. The gaseous/liquid working fluid is than expanded in the expander 50, which further cools the working fluid. The gaseous/liquid working fluid then passes through the first heat exchanger 20. The working fluid flowing through the first heat exchanger 20 absorbs heat from the second process fluid PF₂, which heats the working fluid flowing through the first heat exchanger 20. The first heat exchanger 20 in the heat pump mode operates as an evaporator that mostly or fully evaporates the working fluid flowing through the first heat exchanger 20. The working fluid then flows from the first heat exchanger 20 through the reversible valve 70 back to the suction inlet 12 of the compressor 10.

In an embodiment, the valves 30, 32, 34, 36, 38, 40, 42 are configured so that the working fluid when flowing through the first heat exchanger 20 in the second flow direction D₂ in the heat pump mode flows through its heat exchange coils 22A, 22B in parallel. In parallel, a portion of the working fluid from the expander 50 passes through the first heat exchange coil 22A and a different portion of the working fluid from the expander 50 passes through the second heat exchange coil 22B. In an embodiment, the valves 38, 40, 42 prevent the working fluid in the heat pump mode from flowing through the heat exchange coils 22A, 22B in series or by-passing all of the heat exchange coils 22A, 22B.

In an embodiment, the working fluid flows through the heat exchange coils 22A, 22B in parallel when the heat exchanger 20 is operating as an evaporator. In an embodiment, heat exchanger coils in parallel provide an ideal pressure drop for operating as an evaporator at a higher efficiency. The first heat exchanger 20 can advantageously have a higher efficiency in the heat pump mode when operating as an evaporator by the working fluid flowing through its heat exchange coils 22A, 22B in parallel.

In the heat pump mode, the working fluid flowing from expander 50 through the first heat exchanger 20 to the reversing valve 70 passes through four of the valves 30, 32, 34, 36 and three of the valves 38, 40, 42 block working fluid. As shown by comparing FIGS. 2A and 2B, the working fluid passes through the valves 30, 32, 34, 36 that had blocked working fluid in the cooling mode, while the valves 38, 40, 42 now block working fluid in the heat pump mode instead of having working fluid passing through.

As shown in FIG. 2B, the fifth valve 38, the sixth valve 40, and the seventh valve 42 each block working fluid when the working fluid is flowing through the first heat exchanger 20 in the second direction D₂. The working fluid flows through the first valve 30, the second valve 32, the third valve 34, and the fourth valve 36 when flowing through the first heat exchanger 20 in the second direction D₂.

In the heat pump mode, the second valve 32 is downstream of the first heat exchange coil 22A while the fourth valve 36 is upstream of the first heat exchange coil 22A, and the first valve 30 is downstream of the second heat exchange coil 22B while the third valve 34 is upstream of the second heat exchange coil 22B. A portion of the working fluid flows through the first heat exchanger 20 by flowing through the fourth valve 36, the first heat exchange coil 22A, and then the second valve 32. A different portion of the working fluid flows through the first heat exchanger 20 by flowing through the third valve 34, the second heat exchange coil 22B, and then the first valve 30.

In a heat pump mode, the fifth valve 38, the sixth valve 40, the seventh valve 42 each connect upstream of the heat exchange coils 22A, 22B. The fifth valve 38, the sixth valve 40, and the seventh valve 42 each separately prevent the working fluid from bypassing the heat exchange coils 22A, 22B. In an embodiment, the fifth valve 38, the sixth valve 40, and the seventh valve 42 each separately prevent the working fluid from bypassing the heat exchange coils 22A, 22B through the third branch 28C, the second branch 28B, and the first branch 28A, respectively.

As shown in FIG. 2A, in the cooling mode working fluid flows through the first heat exchange coil 22A in a flow direction D_(22A) while working fluid flows through the second heat exchange coil 22B in a flow direction D_(22B). As shown in FIG. 2B, in the heat pump mode working fluid flows through the first heat exchange coil 22A in the flow direction D_(22A) while working fluid flows through the second heat exchange coil 22B in the flow direction D_(22B). The first process fluid PF₁ flows through the heat exchange coils 22A, 22B of the heat exchanger 120 in parallel. In an embodiment, the flow directions in each of the heat exchange coils 22A, 22B does not change between the cooling mode and the heat pump mode in the heat transfer circuit 1. In an embodiment, this can advantageously allow first process fluid PF₁ and working fluid in each heat exchange coil 22A, 22B to be in counter-flow in both the cooling mode and the heat pump mode, which can provide increased heat transfer and efficiency.

The first process fluid PF₁ in FIGS. 1-2B flows through the first heat exchanger 20 in the first direction D₁ The first process fluid PF₁ and the working fluid flow through the first heat exchange coil 22A in counter-flow. It should be appreciated that the flow of the first process fluid PF₁ through the first heat exchanger 20 as shown in FIGS. 1-2B may be reversed in an embodiment. In an embodiment, the first process fluid PF₁ may flow through the heat exchanger coils 22A, 22B in parallel in the reverse direction (e.g., in the second direction D₂). In an embodiment, heat transfer circuit 1 may be configured so that the first process fluid PF₁ flows through the heat exchange coils 22A, 22B in parallel with the flow of the first process fluid PF₁ through one of the coils heat exchange coils 22A, 22B being reversed. In an embodiment, a portion of the first process fluid PF₁ flows through the first heat exchange coil 22A in one direction (e.g., the first direction D₁, the second direction D₂) and a different portion of the first process fluid PF₁ flows through the second heat exchange coil 22B in an opposite direction. In an embodiment, the first process fluid PF₁ may flow to and from the first heat exchanger 20 through a reversing valve (not shown). The reversing valve may be controlled to reverse the flow of the first process fluid PF₁ through the first heat exchanger 20 based on the mode of the heat transfer circuit 1.

In an embodiment, the first heat exchanger 20 includes a plurality of heat exchange coils 22A, 22B. In an embodiment, the first heat exchanger 20 includes a first heat exchange coil 22A and a second heat exchange coil 22B. However, it should be appreciated that the first heat exchanger 20 in an embodiment may have more than two heat exchange coils 22A, 22B. In an embodiment, the reversible main flow path 5 may further include an additional branch with a configuration similar to the second branch 28B, and an additional valve with a configuration similar to the fourth valve 36 for each additional heat exchange coil. For example, the heat transfer circuit 1 in an embodiment may include a third heat exchange coil (not shown) that fluidly connects the third branch 28A and a fourth branch (not shown) with a similar configuration to the second branch, and an additional valve (not shown) with a similar configuration to the fourth valve 36 blocks working fluid to prevent the working fluid from bypassing the third heat exchange coil in the cooling mode.

FIG. 3 is a schematic diagram of a heat transfer circuit 101 according to an embodiment. In an embodiment, the heat transfer circuit 101 may be employed in an HVACR system. The heat transfer circuit 101 is similar to the heat transfer circuit 1 in FIG. 1, except with respect to the configuration of the portion of the reversible main flow path 105 between a reversing valve 170 and an expander 150. For example, the heat transfer circuit 101 includes a compressor 110 with a suction inlet 112 and a discharge outlet 114, a first heat exchanger 120 with a first heat exchange coil 122A and a second heat exchange coil 122B, the expander 150, a second heat exchanger 160, the reversing valve 170, and a controller 190 similar to the heat transfer circuit 1 in FIG. 1.

In an embodiment, the heat transfer circuit 101 is configured to be changed between a cooling mode and a heat pump mode using the reversing valve 170 similar to the heat transfer circuit 1 in FIG. 1 and as discussed above. The reversible valve 170 can change a flow direction through the reversible main flow path 105 for the working fluid that extends from the reversing valve 170, through the first heat exchanger 120, the expander 150, and the second heat exchanger 160, and back to the reversible valve 170. In an embodiment, the controller 190 may control the reversible valve 170 as similarly discussed above for the controller 90 in FIG. 1. In an embodiment, the controller 190 may be a controller of the HVACR system. The working fluid flows through first heat exchanger 120, through the expander 150, and then through the second heat exchanger 160 in the cooling mode. The working fluid flows through the second heat exchanger 160, through the expander 150, and then through the first heat exchanger 120 in the heat pump mode.

In the cooling mode, a first process fluid PF₁ flowing through the first heat exchanger 120 is heated by the working fluid, and a second process fluid PF₂ flowing through the second heat exchanger 160 is cooled by the working fluid. In the heat pump mode, the first process fluid PF₁ is cooled in the first heat exchanger 120 by the working fluid, and the second process fluid PF₂ is heated in the second heat exchanger 160. As similarly discussed regarding the heat transfer circuit 1 in FIG. 1, the heat transfer circuit 101 in an embodiment may include additional components than those shown in FIG. 3.

Similar to the heat transfer circuit 1 in FIG. 1, working fluid is directed differently through the heat exchange coils 122A, 122B of the first heat exchanger 120 based on the flow direction of the working fluid through the first heat exchanger 120. The flow direction of the working fluid changes when the heat transfer circuit 101 changes between the cooling mode and the heat pump mode. The change in the flow direction of the working fluid through the first heat exchanger 120 also changes whether the first heat exchanger 120 heats the working fluid or absorbs heat from the working fluid. In an embodiment, the heat transfer circuit 101 is configured to direct flow through the plurality of heat exchange coils 122A, 122B differently based on the mode of the heat transfer circuit 101. The working fluid flows through the plurality of heat exchange coils 122A, 122B in parallel or series based on the flow direction through the first heat exchanger 120.

In an embodiment, the heat transfer circuit includes valves 130, 132, 134 that are configured to direct the working fluid through the plurality of heat exchange coils 122A, 122B in parallel or series depending upon the flow direction through the first heat exchanger 120. The working fluid flows through the plurality of heat exchange coils 122A, 122B in series when the heat transfer circuit 101 is operating in the cooling mode, and flows through the plurality of heat exchange coils 122A, 122B in parallel when the heat transfer circuit 101 is operating in the heat pump mode.

In an embodiment, the reversible main flow path 105 splits into two branches 128A, 128B before the heat exchange coils 122A, 122B and the two branches 128A, 128B converge after the heat exchange coils 122A, 122B. The two branches 128A, 128B diverge and diverge between the reversing valve 170 and the expander 150. In an embodiment, the two branches 128A, 128B, before converging, are fluidly connected by the second heat exchange coil 122B. In an embodiment, the first branch 128A includes the first heat exchange coil 122A.

In an embodiment, the valves 130, 132, 134 are check valves. The check valves 130, 132, 134 passively direct the working fluid. Thus, the check valves 130, 132, 134, can provide the desired series/parallel routing of the working fluid through the heat exchange coils 122A, 122B without needing additional active controls. Alternatively, the valves 130, 132, 134 in an embodiment may be control valve(s), and a controller (e.g., the controller 190) may be configured to close and/or open the control valve(s) to respectively block and/or allow the working fluid as described below.

FIG. 4A is a schematic diagram of the heat transfer circuit 101 when operating in the cooling mode. The flow path of the working fluid through the heat transfer circuit 101 is shown in bold lines. Dashed lines are illustrated in the reversible valve 170 for the flow paths that are closed. In the cooling mode, compressed working fluid flows from the discharge outlet 114 of the compressor 110 through the reversible valve 170 valve to the first heat exchanger 120, from the first heat exchanger 120 to the expander 150, from the expander 150 to the second heat exchanger 160, and from the second heat exchanger 160 through the reversible valve 170 to the suction inlet 112 of the compressor 110. The working fluid flows from the reversible valve 170 through the first heat exchanger 120 in a first direction D₁ to the expander 150.

In an embodiment, when operating in the cooling mode, the valves 130, 132, 134 are configured so that the working fluid flowing through the first heat exchanger 120 in the first flow direction D₁ flows through its heat exchange coils 122A, 122B in series. In an embodiment, the working fluid passes through the first heat exchange coil 122A, passes through the second heat exchange coil 122B, and then flows to the expander 150. The first process fluid PF₁ flows through all of the heat exchange coils 122A, 122B in parallel similar to the first process fluid PF₁ in the first heat transfer circuit 1 in FIG. 1. In an embodiment, the valves 130, 132, 134 prevent the working fluid from flowing through the heat exchange coils 122A, 122B in parallel or by-passing one or more of the heat exchange coils 122A, 122B in the cooling mode.

In an embodiment, three valves 130, 132, 134 direct the working fluid through heat exchange coils 122A, 122B of the first heat exchanger 120. The valves 130, 132, 134 are located between the reversing valve 170 and the expander 150. In the cooling mode, the working fluid flowing from the reversing valve 170 through the first heat exchanger 120 to the expander 150 flows through one of the valves 134 and two of the valves 130, 132 block working fluid.

As shown in FIG. 4A, a first valve 130 and a second valve 132 each block working fluid when the working fluid is flowing through the first heat exchanger 120 in the first direction D₁ in the cooling mode. The working fluid flows through a third valve 134 to the expander 150. In an embodiment, the first branch 128A includes the first valve 130, and the second branch 128B includes the second valve 132 and the third valve 134.

The first valve 130 is between the first heat exchange coil 122A and the expander 150 and between the second heat exchange coil 122B and the expander 150. In the cooling mode, the first valve 130 connects downstream of the first heat exchange coil 122A and upstream of the second heat exchange coil 122B and connects downstream of the heat exchange coils 122A, 122B. In the cooling mode, the first valve 130 prevents the working fluid from bypassing the second heat exchange coil 122B after passing through the first heat exchange coil 122A.

The second valve 132 is between the reversing valve 170 and the second heat exchange coil 122B. The second valve 132 is also between the reversing valve 170 and the third valve 134. In the cooling mode, the second valve 132 connects upstream of the heat exchange coils 122A, 122B and connects downstream of the heat exchange coils 122A, 122B. In the cooling mode, the second valve 132 prevents the working fluid flowing from the reversing valve 170 from bypassing the heat exchange coils 122A, 122B.

The third valve 134 is between the second heat exchange coil 122B and the expander 150. The third valve 134 is also between the second valve 132 and the expander 150. In the cooling mode, the third valve 134 is downstream of the second heat exchange coil 122B and the working fluid flows through the third valve 134 after flowing through the heat exchange coil 122B.

FIG. 4B is a schematic diagram of the heat transfer circuit 101 when operating in the heat pump mode. FIG. 4B includes bold lines to show the flow path of the working fluid through the heat transfer circuit 101 in the heat pump mode. Dashed lines are illustrated in the reversible valve 170 for the flow paths that are closed. Similar to the heat transfer circuit 1 in FIG. 2B, in the heat pump mode, compressed working fluid flows from the discharge outlet 114 of the compressor 110 through the reversible valve 170 valve to the second heat exchanger 160, from the second heat exchanger 160 to the expander 150, from the expander 150 to the first heat exchanger 120, and from the first heat exchanger 120 through the reversible valve 170 to the suction inlet 112 of the compressor 110. The working fluid flows from the expander 150 through the first heat exchanger 120 in a second direction D₂ to the reversible valve 170.

In an embodiment, the valves 130, 132, 134 are configured so that the working fluid flowing through the first heat exchanger 120 in the second direction D2 in the heat pump mode flows through its heat exchange coils 122A, 122B in parallel. A portion of the working fluid from the expander 150 passes through the first heat exchange coil 122A and a different portion of the working fluid from the expander 150 passes through the second heat exchange coil 122B. In the heat pump mode, the working fluid is prevented from flowing through the heat exchange coils 122A, 122B in series or by-passing the heat exchange coils 122A, 122B entirely.

In an embodiment, the working fluid when flowing through the first heat exchanger 120 in the second direction D₂ in the heat pump mode passes through two of the valves 130, 132 and one of the valves 134 blocks working fluid. As shown by comparing FIGS. 4A and 4B, the working fluid passes through the valves 130, 132 that had blocked working fluid in the cooling mode, while the valve 134 now blocks working fluid in the heat pump mode.

As shown in FIG. 4B, the third valve 134 blocks working fluid when the working fluid is flowing through the first heat exchanger in the second direction D₂ in the heat pump mode. The working fluid when flowing through the first heat exchanger 120 in the second direction D₂ in the heat pump mode flows through the first valve 130 and the second valve 132.

In the heat pump mode, the first valve 130 is upstream of the heat exchange coils 122A, 122B, and working fluid flows through the first valve 130 and then splits to flow into the heat exchange coils 122A, 122B. In the heat pump mode, the second valve 132 is downstream of the first heat exchange coil 122A. A portion of the working fluid flows through the first heat exchanger 120 by flowing through the first valve 130 and then the first heat exchange coil 122A. A different portion of the working fluid flows through the first heat exchanger 120 by flowing through the first valve 130, the second heat exchange coil 122B, and then the second valve 132.

In the heat pump mode, the third valve 134 connects upstream of the heat exchange coils 122A, 122B and connects downstream of the second heat exchange coil 122B. In the heat pump mode, the third valve 134 prevents the working fluid flowing from the expander 150 from bypassing the heat exchange coils 122A, 122B.

As shown in FIG. 4A, in the cooling mode working fluid flows through the first heat exchange coil 122A in a flow direction D_(122A-1) while working fluid flows through the second heat exchange coil 122B in a flow direction D_(122B). As shown in FIG. 4B, in the heat pump mode, working fluid flows through the first heat exchange coil 122A in the flow direction D_(122A-2) while working fluid flows through the second heat exchange coil 122B in the flow direction D_(122B). The first process fluid PF₁ flows through the heat exchange coils 122A, 122B of the heat exchanger 120 in parallel. In an embodiment, the flow direction D_(122B) of working fluid through the second heat exchange coil 122B is the same in both the cooling mode and the heat pump mode. In an embodiment, this can advantageously allow for the first process fluid PF₁ and the working fluid in second heat exchange coil 122B to be in counter-flow in both the cooling mode and the heat pump mode, which can provide increased heat transfer and efficiency. The flow direction D_(122A-1), D_(122A-2) of working fluid through the first heat exchange coil 122A changes is reversed between the heat pump mode and the cooling mode.

The first process fluid PF₁ in FIGS. 3-4B flows through the first heat exchanger 120 in the second direction D₂ The first process fluid PF₁ flows through the heat exchange coils 122A, 122B of the heat exchanger 120 in parallel. In an embodiment, the first process fluid PF₁ and the working fluid flow through the first heat exchange coil 122A in counter-flow in the cooling mode and in the same flow direction in the heat pump mode. It should be appreciated that the flow of the first process fluid PF₁ through the first heat exchanger 120 as shown in FIGS. 3-4B may be reversed in an embodiment as similarly discussed above with respect to the flow of the first process fluid PF₁ in FIGS. 1-2B.

The heat exchanger 120 shown in FIG. 3 includes the two heat exchange coils 122A, 122B. However, it should be appreciated that the heat exchanger 120 in an embodiment may have more than two heat exchange coils 122A, 122B. In such an embodiment, the heat transfer circuit may include more of the valves 130, 132, 134 and the branches 128A, 128B so that the working fluid is properly directed through each of the additional heat exchange coils in parallel/series as discussed above for the heat exchange coils 122A, 122B. In an embodiment, the reversible main flow path 105 may further include an additional branch (not shown) with a similar configuration to the second branch 128A and an additional valve (not shown) with a similar configuration to the first valve 130 for each additional heat exchange coil. For example, heat transfer circuit 101 in an embodiment may include a third heat exchanger coil (not shown) that connects the second branch 128B to a third branch (not shown) that has a similar configuration to the second branch 128B, and an additional valve (not shown) with a similar configuration to the first valve 130 is in second branch 128B and blocks working fluid to prevent the working fluid from bypassing the third heat exchange coil in the cooling mode.

FIG. 5 is a schematic diagram of a heat transfer circuit 201 according to an embodiment. In an embodiment, the heat transfer circuit 201 may be employed in an HVACR system. The heat transfer circuit 201 is similar to the heat transfer circuit 1 in FIG. 1, except with respect to the configuration of the portion of the reversible main fluid path 205 between a reversing valve 270 and an expander 250. For example, the heat transfer circuit 201 includes a compressor 210 with a suction inlet 212 and a discharge outlet 214, a first heat exchanger 220 with a first heat exchange coil 222A and a second heat exchange coil 222B, an expander 250, a second heat exchanger 260, the reversing valve 270, and a controller 290.

The heat transfer circuit 201 is configured to be changed between a cooling mode and a heat pump mode using the reversing valve 270 similar to the heat transfer circuit 1 in FIG. 1 and as discussed above. The reversible valve 270 can change a flow direction through the reversible main flow path 205 for the working fluid that extends from the reversing valve 270, through the first heat exchanger 220, the expander 250, and the second heat exchanger 260, and back to the reversible valve 270. In an embodiment, the controller 290 may control the reversible valve 270 as similarly discussed above for the controller 90 in FIG. 1. In an embodiment, the controller 290 may be a controller of the HVACR system. The working fluid flows through the first heat exchanger 220, through the expander 250, and then through the second heat exchanger 260 in the cooling mode. The working fluid flows through the second heat exchanger 260, through the expander 250, and then through the first heat exchanger 220 in the heat pump mode.

In the cooling mode, a first process fluid PF₁ flowing through the first heat exchanger 220 is heated by the working fluid, and a second process fluid PF₂ flowing through the second heat exchanger 260 is cooled by the working fluid. In the heat pump mode, the first process fluid PF₁ is cooled in the first heat exchanger 220 by the working fluid and the second process fluid PF₂ is heated in the second heat exchanger 260. As similarly discussed regarding the heat transfer circuit 1 in FIG. 1, the heat transfer circuit 201 in an embodiment may include additional components than those shown in FIG. 5.

Similar to the heat transfer circuit 1 in FIG. 1, the heat transfer circuit 201 is configured to direct flow through the heat exchange coils 222A, 222B of the first heat exchanger 220 based on the flow direction of the working fluid through the first heat exchanger 220. The flow direction of the working fluid through the first heat exchanger 220 changes when the heat transfer circuit 201 changes between the cooling mode and the heat pump mode. The heat transfer circuit 201 is configured to direct flow through the plurality of heat exchange coils 222A, 222B differently based on the mode of the heat transfer circuit 201. The working fluid flowing through the plurality of heat exchange coils 222A, 222B in parallel or series based on the flow direction through the first heat exchanger 220.

In an embodiment, the heat transfer circuit includes valves 230, 232, 234 that are configured to direct the working fluid through the plurality of heat exchange coils 222A, 222B in parallel or series depending upon the flow direction through the first heat exchanger 220. The working fluid flows through the plurality of heat exchange coils 222A, 222B in series when the heat transfer circuit 201 is operating in the cooling mode. The working fluid flows through the plurality of heat exchange coils 222A, 222B in parallel when the heat transfer circuit 201 is operating in the heat pump mode.

In an embodiment, the reversible main flow path 205 splits into two branches 228A, 228B before the heat exchange coils 222A, 222B and the two branches 228A, 228B converge after the heat exchange coils 222A, 222B. The diverging and converging of the reversible main flow path 205 into/from the two branches 228A, 228B both occur between the reversing valve 270 and the expander 250. In an embodiment, the two branches 228A, 228B, before converging, are fluidly connected by the second heat exchange coil 222B. In an embodiment, the first branch 228A includes the first heat exchange coil 222A. In an embodiment, the second branch 228B does not include a heat exchange coil 222A, 222B.

In an embodiment, the valves 230, 232, 234 are check valves. The check valves 230, 232, 234 passively direct the working fluid. Thus, the check valves 230, 232, 234, can provide the desired series/parallel routing of the working fluid through the heat exchange coils 222A, 222B without needing additional active controls. Alternatively, the valves 230, 232, 234 in an embodiment may be control valves, and a controller (e.g., the controller 290) may be configured to close or open the valve(s) to respectively block and/or allow working fluid as described above.

FIG. 6A is a schematic diagram of the heat transfer circuit 201 when operating in the cooling mode. The flow path of the working fluid through the heat transfer circuit 201 is shown in bold lines. Dashed lines are illustrated in the reversible valve 270 for the flow paths that are closed. In the cooling mode, compressed working fluid flows from the discharge outlet 214 of the compressor 210 through the reversible valve 270 valve to the first heat exchanger 220, from the first heat exchanger 220 to the expander 250, from the expander 250 to the second heat exchanger 260, and from the second heat exchanger 260 through the reversible valve 270 to the suction inlet 212 of the compressor 210. The working fluid flows from the reversible valve 270 through the first heat exchanger 220 in a first direction D₁ to the expander 250.

In an embodiment, when operating in the cooling mode, the valves 230, 232, 234 are configured so that the working fluid flowing through the first heat exchanger 220 in the first direction D₁ in the cooling mode flows through its heat exchange coils 222A, 222B in series. In an embodiment, the working fluid passes through the first heat exchange coil 222A, passes through the second heat exchange coil 222B, and then flows to the expander 250. The first process fluid PF₁ flows through each of the coils 222A, 222B and in parallel similar to the first process fluid PF₁ in the first heat transfer circuit 1 in FIG. 1. In an embodiment, the valves 230, 232, 234 prevent the working fluid from flowing through the heat exchange coils 222A, 222B in parallel or by-passing one or more of the heat exchange coils 222A, 222B in the cooling mode.

In an embodiment, three valves 230, 232, 234 direct the working fluid through heat exchange coils 222A, 222B of the first heat exchanger 220. The valves 230, 232, 234 are located between the reversing valve 270 and the expander 250. In the cooling mode, the working fluid flowing from the reversing valve 270 through the first heat exchanger 220 to the expander 250 flows through one of the valves 234 and two of the valves 230, 232 block working fluid.

As shown in FIG. 6A, a first valve 230 and a second valve 232 each block working fluid when the working fluid is flowing through the first heat exchanger 220 in the first direction D₁ in the cooling mode. The working fluid flows through a third valve 234 to the expander 250. In an embodiment, the first branch 228A includes the first valve 230 and the second branch 228B includes the second valve 232 and the third valve 234.

The first valve 230 is between the first heat exchange coil 222A and the expander 250 and between the second heat exchange coil 222B and the expander 250. In the cooling mode, the first valve 230 connects downstream of the first heat exchange coil 222A and upstream of the second heat exchange coil 222B and connects downstream of the heat exchange coils 222A, 222B. In the cooling mode, the first valve 230 prevents the working fluid from bypassing the second heat exchange coil 222B after passing through the first heat exchange coil 222A.

The second valve 232 is between the reversing valve 270 and the second heat exchange coil 222B. The second valve 232 is also between the reversing valve 270 and the third valve 234. In the cooling mode, the second valve 232 connects upstream of the heat exchange coils 222A, 222B and connects downstream of the heat exchange coils 222A, 222B. In the cooling mode, the second valve 232 prevents the working fluid flowing from the reversing valve 270 from bypassing the heat exchange coils 222A, 222B.

The third valve 234 is between the second heat exchange coil 222B and the expander 250. The third valve 234 is also between the second valve 232 and the expander 250. In the cooling mode, third valve 234 is downstream of the second heat exchange coil 222B and the working fluid flows through the third valve 234 after flowing through each of the coils 222A, 222B.

FIG. 6B is a schematic diagram of the heat transfer circuit 201 when operating in the heat pump mode. FIG. 6B includes bold lines to show the flow path of the working fluid through the heat transfer circuit 201 in the heat pump mode. Dashed lines are illustrated in the reversible valve 270 for the flow paths that are closed. Similar to the heat transfer circuit 1 in FIG. 2B, in the heat pump mode, compressed working fluid flows from the discharge outlet 214 of the compressor 210 through the reversible valve 270 valve to the second heat exchanger 260, from the second heat exchanger 260 to the expander 250, from the expander 250 to the first heat exchanger 220, and from the first heat exchanger 220 through the reversible valve 270 to the suction inlet 212 of the compressor 210. The working fluid flows from the expander 250 through the first heat exchanger 220 in a second direction D₂ to the reversible valve 270.

In an embodiment, the valves 230, 232, 234 are configured so that the working fluid flowing through the first heat exchanger 220 in the second direction D₂ in a heat pump mode flows through its heat exchange coils 222A, 222B in parallel. A portion of the working fluid from the expander 250 passes through the first heat exchange coil 222A and a different portion of the working fluid from the expander 250 passes through the second heat exchange coil 222B. In the heat pump mode, the working fluid is prevented from flowing through the heat exchange coils 222A, 222B in series or by-passing the heat exchange coils 222A, 222B entirely.

In an embodiment, the three valves 230, 232, 234 direct working fluid through the heat exchange coils 222A, 222B of the first heat exchanger 220. In the heat pump mode, the working fluid flowing from expander 250 through the first heat exchanger 220 to the reversing valve 270 passes through two of the valves 230, 232, and one of the valves 234 blocks working fluid. As shown by comparing FIGS. 6A and 6B, the working fluid passes through the valves 230, 232 that had blocked working fluid in the cooling mode, while the valve 234 now blocks working fluid in the heat pump mode.

As shown in FIG. 6B, the third valve 234 blocks working fluid when the working fluid is flowing through the first heat exchanger 220 in the second direction D₂ in the heat pump mode. The working fluid flows through the first valve 230 and the second valve 232 when flowing from the expander 250 through the first heat exchanger 220 to the reversing valve 270.

In the heat pump mode, the first valve 230 is upstream the heat exchange coils 222A, 222B, and working fluid flows through the first valve 230 and then splits to flow into the heat exchange coils 222A, 222B. In the heat pump mode, the second valve 232 is downstream of the second heat exchange coil 222B and connects downstream of the first heat exchange coil 222B. A portion of the working fluid flows through the first heat exchanger 220 by flowing through the first valve 230 and then the first heat exchange coil 222A. A portion of the working fluid flows through the first heat exchanger 220 by flowing through the first valve 230, the second heat exchange coil 222B, and then the second valve 232.

In the heat pump mode, the third valve 234 connects upstream of the heat exchange coils 222A, 222B and connects downstream of the second heat exchange coil 222B. The third valve 234 prevents the working fluid flowing from the expander 250 from bypassing the heat exchange coils 222A, 222B.

As shown in FIG. 6A, in the cooling mode working fluid flows through the first heat exchange coil 222A in a flow direction D_(222A-1) while working fluid flows through the second heat exchange coil 222B in a flow direction D_(222B). As shown in FIG. 6B, in the heat pump mode working fluid flows through the first heat exchange coil 222A in the flow direction D_(222A-2), while working fluid flows through the second heat exchange coil 222B in the flow direction D_(222B). The flow direction D_(222B) of working fluid through the second heat exchange coil 222B is the same in both the cooling mode and the heat pump mode. The first process fluid PF₁ flows through the heat exchange coils 222A, 222B in parallel. In an embodiment, this can advantageously allow for the first process fluid PF₁ and the working fluid to be in counter-flow in the second heat exchange coil 222B in both the cooling mode and the heating pump mode, which can provide increased heat transfer and efficiency. The flow direction D_(222A-1), D_(222A-2) of working fluid through the first heat exchange coil 222A is reversed between the heat pump mode and the cooling mode.

The first process fluid PF₁ in FIGS. 5-6B flows through the first heat exchanger 220 in the first direction D₁ The first process fluid PF₁ flows through the heat exchange coils 222A, 222B of the heat exchanger 220 in parallel. The first process fluid PF₁ and the working fluid flow through the first heat exchange coil 222A in the same direction in the cooling mode and in counter-flow in the heat pump mode. It should be appreciated that the flow of the first process fluid PF₁ through the first heat exchanger 220 as shown in FIGS. 5-6B may be reversed in an embodiment as similarly discussed above with respect to the flow of the first process fluid PF₁ in FIGS. 1-2B.

The heat exchanger 220 shown in FIG. 5 includes the two heat exchange coils 222A, 222B. However, it should be appreciated that the heat exchanger 220 in an embodiment may have more than two heat exchange coils 222A, 222B. In such an embodiment, the heat transfer circuit 201 may include more valves 230, 232, 234, and branches 228A, 228B, so that the working fluid is properly directed through each of the additional heat exchange coils in parallel/series as discussed above for the heat exchange coils 222A, 222B. In an embodiment, the reversible main flow path 205 may further include an additional branch (not shown) with a similar configuration to the second branch 228B and an additional valve (not shown) with a similar configuration to the first valve 230 for each additional heat exchange coil. For example, the heat transfer circuit 201 in an embodiment may include a third heat exchange coil (not shown) that connects the second branch 228B to a third branch (not shown) that has a similar configuration to the second branch 228B, and an additional valve (not shown) with a similar configuration to the first valve 230 blocks working fluid from bypassing the third heat exchange coil in the cooling mode.

FIG. 7 is a schematic diagram of a heat transfer circuit 301 according to an embodiment. In an embodiment, the heat transfer circuit 301 may be employed in an HVACR system. The heat transfer circuit 301 has the same configuration as the heat transfer circuit 201 in FIGS. 5-6B, except that the valves 230, 232, 234 are replaced with valves 330, 332. For example, the heat transfer circuit 301 includes a compressor 310 with a suction inlet 312 and a discharge outlet 314, a first heat exchanger 320 with a first heat exchange coil 322A and a second heat exchange coil 322B, an expander 350, a second heat exchanger 360, the reversing valve 370, and a controller 390.

The heat transfer circuit 301 is configured to be changed between a cooling mode and a heat pump mode using the reversing valve 370 similar to the heat transfer circuit 1 in FIG. 1 and as discussed above. The reversible valve 370 can change a flow direction through the reversible main flow path 305 for the working fluid that extends from the reversing valve 370, through the first heat exchanger 320, the expander 350, and the second heat exchanger 360, and back to the reversible valve 370. In an embodiment, the controller 390 may control the reversible valve 370 as similarly discussed above for the controller 90 in FIG. 1. In an embodiment, the controller 390 may be a controller of the HVACR system. The flows through the heat transfer circuit 301 and the heat exchange coils 322A, 322B are similar to the heat transfer circuit 201, except that the flows through the heat exchange coils 322A, 322B are directed using the valves 330, 332 instead of the valves 230, 232, 234. For example, the reversible main fluid path 305 between a reversing valve 370 and an expander 350 splits into two branches 328A, 328B similar to the reversible main flow path 205 in FIG. 6A. The heat transfer circuit 301 has similar features as the heat transfer circuit 201 unless described otherwise.

In an embodiment, the reversible main flow path 305 splits into two branches 328A, 328B before the heat exchange coils 322A, 322B and the two branches 328A, 328B converge after the heat exchange coils 322A, 322B. The diverging and converging of the reversible main flow path 305 into/from the two branches 328A, 328B both occur between the reversing valve 370 and the expander 350. In an embodiment, the two branches 328A, 328B converge at the first valve 330. In an embodiment, the two branches 328A, 328B, before converging, are fluidly connected by the second heat exchange coil 322B. In an embodiment, the first branch 328A includes the first heat exchange coil 322A. In an embodiment, the second branch 328B does not include a heat exchange coil 322A, 322B.

In an embodiment, the valves 330, 332 are three-way valves that have three inlet(s)/outlet(s). The three-way valves 330, 332 each have two positions that fluidly connect two of the inlet(s)/outlet(s), and blocks a third inlet/outlet. In an embodiment, the controller 390 controls the positions of the three-way valves 330, 332. In an embodiment, the position of each the three-way valve 330, 332 is changed when the heat transfer circuit 301 is changed between a cooling mode and a heat pump mode.

FIG. 8A is a schematic diagram of the heat transfer circuit 301 when operating in a cooling mode. FIG. 8A includes bold lines to show the flow path of the working fluid through the heat transfer circuit 301 in the heat pump mode. Dashed lines are illustrated in the reversible valve 370, and the valves 330, 332 for the flow paths that are closed. Flow through the heat transfer circuit 301 in the cooling mode is the same as discussed above for the heat transfer circuit 201 in FIG. 6A in the cooling mode. The working fluid flows from the reversible valve 370 through the first heat exchanger 320 in a first direction D₁ to the expander 350.

In an embodiment, two valves 330, 332 direct the working fluid through the two heat exchange coils 322A, 322B of the first heat exchanger 320 based on the flow direction through the first heat exchanger 320. As shown in FIG. 8A, the working fluid in the cooling mode flows through the heat exchange coils 322A in series, and as similarly discussed above for the heat transfer circuit 201 in FIG. 6A. The valves 330, 332 are located between the reversing valve 370 and the expander 350. In the cooling mode, the working fluid flowing from the reversing valve 370 through the first heat exchanger 320 to the expander 340 flows through both of the valves 330, 332, while both of the valves 330, 332 also block working fluid. In an embodiment, the first branch 328A includes the first valve 330 and the second branch 328B includes the first valve 330 and the second valve 332. The first valve 330 converges the two branches 328A, 328B.

The first valve 330 is between the first heat exchange coil 322A and the expander 350 and between the second heat exchange coil 322B and the expander 350. The first valve 330 is also between the second valve 332 and the expander 350. In the cooling mode, the first valve 330 is downstream of the first heat exchange coil 322A and connects upstream of the second heat exchange coil 322B. In the cooling mode, the first valve 330 prevents the working fluid from bypassing the second heat exchange coil 322B after passing through the first heat exchange coil 322A.

The second valve 332 is between the second heat exchange coil 322B and the expander 350. The second valve 332 is also between the reversing valve 370 and the first valve 330. In the cooling mode, the second valve 332 is downstream of the heat exchange coils 322A, 322B and connects upstream of the heat exchange coils 322A, 322B. In the cooling mode, the second valve 332 prevents the working fluid flowing from the reversing valve 370 from bypassing the heat exchange coils 322A, 322B.

FIG. 8B is a schematic diagram of the heat transfer circuit 301 when operating in a heat pump mode. FIG. 8B includes bold lines to show the flow path of the working fluid through the heat transfer circuit 301 in the heat pump mode. Dashed lines are illustrated in the reversible valve 370, and the valves 330, 332 for the flow paths that are closed. Flow through the heat transfer circuit 301 in the heat pump mode is the same as discussed above for the heat transfer circuit 301 in FIG. 6B in the heat pump mode. The working fluid flows from the expander 350 through the first heat exchanger 320 in a second direction D₂ to the reversible valve 370.

In the heat pump mode, the working fluid flows through the heat exchange coils 322A, 322B of the first heat exchanger 380 in parallel as shown in FIG. 8B, and as similarly discussed above for the heat transfer circuit 201 in FIG. 6B. The valves 330, 332 are located between the reversing valve 370 and the expander 350. In the heat pump mode, the working fluid flowing from the reversing valve 370 through the first heat exchanger 320 to the expander 340 flows through both of the valves 330, 332, while both of the valves 330, 332 also block working fluid.

In the heat pump mode, the first valve 330 is upstream of the heat exchange coils 322A, 322B and connects downstream of the second heat exchange coil 322B. In the heat pump mode, the working fluid from the expander 350 flows through the first valve 330 and then splits and flows into the heat exchange coils 332A, 332B.

In the heat pump mode, the second valve 332 is downstream of the second heat exchange coil 322B and connects upstream of the heat exchange coils 322A, 322B. In the heat pump mode, a portion of the working fluid flows from the expander 350, through the first valve 330, through the second heat exchange coil 322B, and then through the second valve 332. In the heat pump mode, the first valve 330 and the second valve 332 prevents the working fluid flowing from the expander 350 from bypassing heat exchange coils 322A, 332B and from flowing through the heat exchange coils 322A, 322B in series.

The heat transfer circuit 301 is an embodiment in which the valves 230, 232, 234 in the heat transfer circuit 201 in FIG. 5 are replaced with the two three-way valves 330, 332. In an embodiment, the heat transfer circuit 101 may be modified in a similar manner. In a similar manner, it should be appreciated that an embodiment of a heat transfer circuit may the same features as the heat transfer circuit 101 in FIG. 3, except that the valves 130, 132, 134 with two three-way valves (e.g., valve 330, valve 332) similar to the heat transfer circuit 301.

The first process fluid PF₁ in FIGS. 7-8B flows through the first heat exchanger 320 in the first direction D₁ The first process fluid PF₁ flows through the heat exchange coils 22A, 22B of the heat exchanger 120 in parallel. The first process fluid PF₁ and the working fluid flow through the first heat exchange coil 322A in the same flow direction in the cooling mode and in counter-flow in the heat pump mode. It should be appreciated that the flow of the first process fluid PF₁ through the first heat exchanger 320 as shown in FIGS. 7-8B may be reversed in an embodiment as similarly discussed above with respect to the flow of the first process fluid PF₁ in FIGS. 1-2B.

The heat exchanger 320 shown in FIG. 7 includes the two heat exchange coils 322A, 322B. However, it should be appreciated that the heat exchanger 320 in an embodiment may have more than two heat exchange coils 322A, 322B. In such an embodiment, the heat transfer circuit may include more valves 330, 332 and branches 328A, 328B, so that the working fluid is properly directed through each of the additional heat exchange coils in parallel/series as discussed above for the heat exchange coils 322A, 322B. In an embodiment, the reversible main flow path 305 may further include an additional branch (not shown) with a configuration similar to the second branch 328B and an additional valve (not shown) similar to the first valve 330 for each additional heat exchange coil. For example, the heat transfer circuit 301 in an embodiment may include a third heat exchange coil (not shown) that connects the second branch 328B to a third branch (not shown) with a configuration similar to the second branch 328B, and an additional valve (not shown) with a configuration similar to the first valve 330 splits/converges the reversible main flow path 305 between the expander 350 and the first valve 330.

FIG. 9 is a schematic diagram of a heat transfer circuit 401 according to an embodiment. In an embodiment, the heat transfer circuit 401 may be employed in an HVACR system. The heat transfer circuit 401 is similar to the heat transfer circuit 1 in FIG. 1, except with respect to the configuration of the portion of the reversible main fluid path 405 between a reversing valve 470 and an expander 450. For example, the heat transfer circuit 401 includes a compressor 410 with a suction inlet 412 and a discharge outlet 414, a first heat exchanger 420 with a first heat exchange coil 422A and a second heat exchange coil 422B, the expander 450, a second heat exchanger 460, the reversing valve 470, and a controller 490 similar to the heat transfer circuit 1 in FIG. 1.

The heat transfer circuit 401 is configured to be changed between a cooling mode and a heat pump mode using the reversing valve 470 similar to the heat transfer circuit 1 in FIG. 1 and as discussed above. The reversible valve 470 can change a flow direction through the reversible main flow path 405 for the working fluid that extends from the reversing valve 470, through the first heat exchanger 420, the expander 450, and the second heat exchanger 460, and back to the reversible valve 470. In an embodiment, the controller 490 may control the reversible valve 470 as similarly discussed above for the controller 90 in FIG. 1. In an embodiment, the controller 490 may be a controller of the HVACR system. The working fluid flows through first heat exchanger 420, through the expander 450, and then through the second heat exchanger 460 in the cooling mode. The working fluid flows through the second heat exchanger 460, through the expander 450, and then through the first heat exchanger 420 in the heat pump mode.

In the cooling mode, a first process fluid PF₁ flows through the first heat exchanger 420 and is heated by the working fluid, and a second process fluid PF₂ flows through the second heat exchanger 460 and is cooled by the working fluid. In the heat pump mode, the first process fluid PF₁ is cooled in the first heat exchanger 420 by the working fluid and the second process fluid PF₂ is heated in the second heat exchanger 460. As similarly discussed regarding the heat transfer circuit 1 in FIG. 1, the heat transfer circuit 401 in an embodiment may include additional components than those shown in FIG. 9.

Similar to the heat transfer circuit 1 in FIG. 1, the heat transfer circuit 401 is configured to direct flow through the heat exchange coils 422A, 422B of the first heat exchanger 420 based on the flow direction of the working fluid through the first heat exchanger 420. The flow direction of the working fluid through the first heat exchanger 420 changes when the heat transfer circuit 401 changes between the cooling mode and the heat pump mode. The heat transfer circuit 401 is configured to direct flow through the plurality of heat exchange coils 422A, 422B differently based on the mode of the heat transfer circuit 401. The working fluid flowing through the plurality of heat exchange coils 422A, 422B in parallel or series based on the flow direction through the first heat exchanger 420.

In an embodiment, the heat transfer circuit includes valves 430, 432, 434 that are configured to direct the working fluid through the plurality of heat exchange coils 422A, 422B in parallel or series depending upon the flow direction through the first heat exchanger 420. The working fluid flows through the plurality of heat exchange coils 422A, 422B in series when the heat transfer circuit 401 is operating in the cooling mode, and flows through the plurality of heat exchange coils 422A, 422B in parallel when the heat transfer circuit 401 is operating in the heat pump mode.

In an embodiment, the reversible main flow path 405 splits into two branches 428A, 428B before the heat exchange coils 422A, 422B and the two branches 428A, 428B converge after the heat exchange coils 422A, 422B. The diverging and converging of the reversible main flow path 405 into/from the two branches 428A, 428B both occur between the reversing valve 470 and the expander 450. In an embodiment, each of the branches 428A, 428B includes a respective heat exchange coil 422B, 422A. In an embodiment, the first branch 428A includes the second heat exchange coil 422B and the second branch 428B includes the first heat exchange coil 422A.

In an embodiment, a first valve 430 and a second valve 432 are check valves. The check valves 430, 432 passively direct the working fluid. Thus, the check valves 430, 432 can provide the desired routing of the working fluid through the heat exchange coils 422A, 422B without needing additional active controls. A third valve 434 is a control valve that controlled to be open or closed. When closed, the third valve 434 blocks working fluid. When open, the third valve 434 allows fluid to pass through the valve 434. In an embodiment, the third valve 434 is configured to be open when the heat transfer circuit 401 is in the cooling mode and to be closed when the heat transfer circuit 401 is in the heat pump mode. In an embodiment, the controller 490 is configured to control the third valve 434 as discussed below. In an embodiment, the valves 430, 432 may also be control valve(s), and a controller (e.g., the controller 490) may be configured to close or open to respectively block and/or allow working fluid as discussed below.

FIG. 10A is a schematic diagram of the heat transfer circuit 401 when operating in the cooling mode. The flow path of the working fluid through the heat transfer circuit 401 is shown in bold lines. Dashed lines are illustrated in the reversible valve 470 for the flow paths that are closed. In the cooling mode, compressed working fluid flows from the discharge outlet 414 of the compressor 410 through the reversible valve 470 valve to the first heat exchanger 420, from the first heat exchanger 420 to the expander 450, from the expander 450 to the second heat exchanger 460, and from the second heat exchanger 460 through the reversible valve 470 to the suction inlet 412 of the compressor 410. The working fluid flows from the reversible valve 470 through the first heat exchanger 420 in a first direction D₁ to the expander 450.

In an embodiment, the valves 430, 432, 434 are configured so that the working fluid flowing through the first heat exchanger 420 in the first direction D₁ in the cooling mode flows through its heat exchange coils 422A, 422B in series. In an embodiment, the working fluid passes through the first heat exchange coil 422A, passes through the second heat exchange coil 422B, and then flows to the expander 450. The first process fluid PF₁ flows through each of the heat exchange coils 422A, 422B and in parallel similar to the first process fluid PF₁ in the first heat transfer circuit 1 in FIG. 1. In an embodiment, the valves 430, 432, 434 prevent the working fluid from passing through the heat exchange coils 422A, 422B in parallel or by-passing one or more of the heat exchange coils 422A, 422B in the cooling mode. The working fluid flows from the reversible valve 470 through the first heat exchanger 420 in a first direction D₁ to the expander 450.

In an embodiment, three valves 430, 432, 434 direct the working fluid through the heat exchange coils 422A, 422B of the first heat exchanger 420. The valves 430, 432, 434 are located between the reversing valve 470 and the expander 450. In the cooling mode, the working fluid flowing from the reversing valve 470 through the first heat exchanger 420 to the expander 440 flows through one of the valves 434 and two of the valves 430, 432 block working fluid.

As shown in FIG. 10A, a first valve 430 and a second valve 432 each block working fluid when the working fluid is flowing through the first heat exchanger 420 in the first direction D₁ in the cooling mode. The working fluid flows through the third valve 434 to the expander 450. The third valve 434 is configured to be open when working fluid is flowing through the first heat exchanger in the direction D₁ in the cooling mode. In an embodiment, the first branch 428A includes the first valve 430 and second heat exchange coil 422B, and the second branch 428B includes the second valve 432.

The first valve 430 is between the reversing valve 470 and the second heat exchange coil 422B. In the cooling mode, the first valve 430 connects upstream of the heat exchange coils 422A, 442B and connects downstream of the first heat exchange coil 422A and upstream of the second heat exchange coil 422B. In the cooling mode, the first valve 430 prevents the working fluid flowing from the reversing valve 470 from flowing to the second heat exchange coil 422B and bypassing first heat exchange coil 422A.

The second valve 432 is between the first heat exchange coil 422A and the expander 450. In the cooling mode, the second valve 432 connects downstream of the first heat exchange coil 422A and upstream of the second heat exchange coil 422B and connects downstream of the heat exchange coils 422A, 422B. In the cooling mode, the second valve 432 prevents the working fluid after flowing through the first heat exchange coil 422A from bypassing the second heat exchange coil 422B.

The third valve 434 is between the first heat exchange coil 422A and the second heat exchange coil 422B. The third valve 434 is also between the first valve 430 and the second valve 432. In the cooling mode, the third valve 434 is downstream of the first heat exchange coil 422A and upstream of the second heat exchange coil 422B. In the cooling mode, the working fluid flows through the first heat exchange coil 422A, the third valve 434, and then through the second heat exchanger 422B.

FIG. 10B is a schematic diagram of the heat transfer circuit 401 when operating in the heat pump mode. FIG. 10B includes bold lines to show the flow path of the working fluid through the heat transfer circuit 401 in the heat pump mode. Dashed lines are illustrated in the reversible valve 470 for the flow paths that are closed. Similar to the heat transfer circuit 1 in FIG. 2B, in the heat pump mode, compressed working fluid flows from the discharge outlet 414 of the compressor 410 through the reversible valve 470 valve to the second heat exchanger 460, from the second heat exchanger 460 to the expander 450, from the expander 450 to the first heat exchanger 420, and from the first heat exchanger 420 through the reversible valve 470 to the suction inlet 412 of the compressor 410. The working fluid flows from the expander 450 through the first heat exchanger 420 in a second direction D₂ to the reversible valve 470.

In an embodiment, the valves 430, 432, 434 are configured so that the working fluid flowing through the first heat exchanger 420 in the second direction D₂ in the heat pump mode flows through its heat exchange coils 422A, 422B in parallel. A portion of the working fluid from the expander 450 passes through the first heat exchange coil 422A and a different portion of the working fluid from the expander 450 passes through the second heat exchange coil 422B. In the heat pump mode, the working fluid is prevented from passing through the heat exchange coils 422A, 422B in series or by-passing the heat exchange coils 422A, 422B entirely.

In an embodiment, the three valves 430, 432, 434 direct fluid through the heat exchange coils 422A, 422B of the first heat exchanger 420. The third valve 434 is closed in the heat pump mode. In the heat pump mode, the working fluid flowing from expander 450 through the first heat exchanger 420 to the reversing valve 470 passes through two of the valves 430, 432, and the valve 434 blocks working fluid. As shown by comparing FIGS. 6A and 6B, the working fluid passes through the valves 430, 432 that had blocked working fluid in the cooling mode, while the valve 434 now blocks working fluid in the heat pump mode.

As shown in FIG. 10B, the third valve 434 blocks working fluid when the working fluid is flowing through the first heat exchanger 420 in the second direction D₂ in a heat pump mode. The working fluid flows through the first valve 430 and the second valve 432 when flowing from the expander 450 through the first heat exchanger 420 to the reversing valve 470.

In the heat pump mode, the first valve 430 is downstream of the second heat exchange coil 422B and connects downstream of the first heat exchange coil 422A. In the heat pump mode, the second valve 432 is upstream of the first heat exchange coil 422A and connects upstream of the second heat exchange coil 422B. A portion of the working fluid flows through the first heat exchanger 420 by flowing through the second valve 432 and then the first heat exchange coil 422A. A different portion of the working fluid flows through the first heat exchanger 420 by flowing through the second heat exchange coil 422B and then flowing through the first valve 430.

In the heat pump mode, the third valve 434 connects upstream of the first heat exchange coil 422A and connects downstream of the second heat exchange coil 422B. In the heat pump mode, the third valve 434 prevents the working fluid flowing from the expander 450 from bypassing the heat exchange coils 422A, 422B.

As shown in FIG. 10A, in the cooling mode working fluid flows through the first heat exchange coil 422A in a flow direction D_(422A-1) while working fluid flows through the second heat exchange coil 422B in a flow direction D_(422B-1). As shown in FIG. 10B, in the cooling mode working fluid flows through the first heat exchange coil 422A in the flow direction D_(422A-2) while working fluid flows through the second heat exchange coil 422B in the flow direction D_(422B-2). Thus, in an embodiment, the flow direction D_(422A-1), D_(422A-2) of working fluid through the first heat exchange coil 422A and the second heat exchange coil 422B is reversed between the heat pump mode and the cooling mode.

The first process fluid PF₁ in FIGS. 9-10B flows through the first heat exchanger 420 in the first direction D₁ The first process fluid PF₁ flows through the heat exchange coils 422A, 422B of the heat exchanger 420 in parallel. The first process fluid PF₁ and the working fluid flow through the first heat exchange coil 422A in the same flow direction in the cooling mode and in counter-flow in the heat pump mode. It should be appreciated that the flow of the first process fluid PF₁ through the first heat exchanger 420 as shown in FIGS. 9-10B may be reversed in an embodiment as similarly discussed above with respect to the flow of the first process fluid PF₁ in FIGS. 1-2B.

The heat exchanger 420 shown in FIG. 9 includes the two heat exchange coils 422A, 422B. However, it should be appreciated that the heat exchanger 420 in an embodiment may have more than two heat exchange coils 422A, 422B. In such an embodiment, the heat transfer circuit 401 may include more valves 430, 432, 434, and branches 428A, 428B, so that the working fluid is properly directed through each of the additional heat exchange coils in parallel/series as discussed below for the heat exchange coils 422A, 422B. In an embodiment, the reversible main flow path 405 may further include an additional branch (not shown) with a similar configuration to the second branch 428B, an additional valve (not shown) with a configuration similar to the first valve 430, and an additional valve (not shown) with a configuration similar to the third valve 434 for each additional heat exchange coil. For example, the reversible flow main path 305 in an embodiment may include a third branch (not shown) with a similar configuration to the second branch 428B and that includes a third heat exchange coil (not shown), an additional valve (not shown) disposed in the second branch 428B similar to the first valve 430 in the first branch 428A, and an additional control valve (not shown) with a configuration similar to the third valve 434 and connects the second branch 428A and the third branch and blocks working fluid in the cooling mode.

FIG. 11 is a block diagram of an embodiment of a method 500 of operating a heat transfer circuit. For example, the method may be for operating the heat transfer circuit 1 in FIGS. 1-2B, the heat transfer circuit 101 in FIGS. 3-4B, the heat transfer circuit 201 in FIGS. 5-6B, the heat transfer circuit 301 in FIGS. 7-8B, or the heat transfer circuit 401 in FIGS. 9-10B. In an embodiment, the heat transfer circuit is employed in an HVACR circuit. The method 500 starts at 510.

At 510, the heat transfer circuit operates in a first mode. In an embodiment, operating in the first mode 510 includes compressing a working fluid in a compressor 515 (e.g., compressor 10, compressor 110, compressor 210, compressor 310, compressor 410), and directing the compressed working fluid in a first direction through a first heat exchanger 517, an expander (e.g., expander 50, expander 150, expander 250, expander 350, expander 450), and a second heat exchanger. The first heat exchanger including a plurality of heat exchange coils (e.g., heat exchange coils 22A, 22B; heat exchange coils 122A, 122B; heat exchange coils 222A, 222B; heat exchange coils 322A, 322B; heat exchange coils 422A, 422B). In an embodiment, a process fluid (e.g., first process fluid PF₁, second process fluid PF₂) flows through the first heat exchanger. A different process fluid flows through the second heat exchanger (e.g., first process fluid PF₁, second process fluid PF₂) and exchanges heat with the working fluid. Directing the working fluid through the first heat exchanger in the first direction 517 includes directing the working fluid through the plurality of heat exchange coils of the first heat exchanger in series. In an embodiment, the working fluid is directed through all of the heat exchange coils of the first heat exchanger in series in the first mode. In an embodiment, the first mode is a cooling mode in which the first heat exchanger operates as a condenser that heats the process fluid (e.g., heat exchanger 20, heat exchanger 120, heat exchanger 220, heat exchanger 320, heat exchanger 420). In another embodiment, the first mode is a cooling mode in which the first heat exchanger operates as an evaporator to cool the process fluid (e.g., heat exchanger 60, heat exchanger 160, heat exchanger 260, heat exchanger 360, heat exchanger 460).

In an embodiment, operating in the first mode 310 includes positioning a reversing valve (e.g., reversing valve 70, reversing valve 170, reversing valve 270, reversing valve 370, reversing valve 470) in a first position. The reversing valve in the first position directs the compressed working fluid from the compressor through the first heat exchanger, the expander, and the second heat exchanger in the first direction. The method 500 then proceeds to 520.

At 520, the heat transfer circuit operates in a second mode. In an embodiment, operating in the second mode 520 includes compressing the working fluid in the compressor 525, and directing the compressed working fluid in a second direction through a first heat exchanger 527, an expander (e.g., expander 50, expander 150, expander 250, expander 350, expander 450), and a second heat exchanger. In an embodiment, the second direction is opposite the first direction. Directing the working fluid through the first heat exchanger in the second direction 527 includes directing the working fluid through the plurality of heat exchange coils of the first heat exchanger in parallel. In an embodiment, the working fluid is directed through all of the heat exchange coils of the first heat exchanger in parallel in the first mode. In an embodiment, the second mode is a heat pump mode in which the first heat exchanger operates as an evaporator to cool the process fluid in the heat pump mode (e.g., heat exchanger 20, heat exchanger 120, heat exchanger 220, heat exchanger 320, heat exchanger 420). In another embodiment, the second mode is a heat pump mode in which the first heat exchanger operates as a condenser to heat the process fluid (e.g., heat exchanger 60, heat exchanger 160, heat exchanger 260, heat exchanger 360, heat exchanger 460).

In an embodiment, the method 500 may be modified based on the heat transfer circuit 1, the heat transfer circuit 101, the heat transfer circuit 201, the heat transfer circuit 301, and/or the heat transfer circuit 401 as shown in FIGS. 1-10B and/or as described above. For example, the method 500 may include blocking working fluid with one or more valves.

Aspects:

Any of aspects 1-13 can be combined with any of aspects 14-16.

Aspect 1. A heat transfer circuit operable in at least a first mode and a second mode, the heat transfer circuit comprising:

a compressor to compress a working fluid;

an expander to expand the working fluid;

a first heat exchanger to exchange heat between the working fluid and a first process fluid, the first heat exchanger including a plurality of heat exchange coils, the working fluid flowing through the plurality of heat exchange coils, the first process fluid flowing through the plurality of heat exchange coils in parallel;

a second heat exchanger to exchange heat between the working fluid and a second process fluid,

a reversing valve configured to change a flow direction of the working fluid through the first heat exchanger; and

a plurality of valves configured to direct the working fluid through the plurality of heat exchange coils of the first heat exchanger based on the flow direction of the working fluid through the first heat exchanger,

wherein the working fluid flows through the plurality of heat exchange coils in series when the flow direction is a first direction, and the working fluid flows through the plurality of heat exchange coils in parallel when the flow direction is a second direction.

Aspect 2. The heat transfer circuit of aspect 1, wherein

the first mode is a cooling mode in which the first heat exchanger operates as a condenser that heats the first process fluid with the working fluid,

the second mode is a heat pump mode in which the first heat exchanger operates as an evaporator that cools the second process fluid with the working fluid.

Aspect 3. The heat transfer circuit of either one of aspects 1 or 2, wherein the plurality of valves includes a valve blocking the working fluid in the first mode and allowing working fluid to pass through in the second mode. Aspect 4. The heat transfer circuit of aspect 3, wherein the valve blocks the working fluid in the first mode to prevent the working fluid from bypassing at least one of the plurality of heat exchange coils. Aspect 5. The heat transfer circuit of any one aspects 1-4, further comprising:

a reversible main flow path for the working fluid that extends from the reversible valve through the first heat exchanger, the expander, and the second heat exchanger, and the reversible main flow path including two or more branches that direct the working fluid through the plurality of heat exchange coils.

Aspect 6. The heat transfer circuit of aspect 5, wherein the reversible main flow path splits into the two or more branches between the reversible valve and the first heat exchanger, the two or more branches converging back into the reversible main flow path between the first heat exchanger and the expander. Aspect 7. The heat transfer circuit of either one of aspects 5 or 6, wherein the two or more branches include a first branch and a second branch, the plurality of heat exchange coils including a first heat exchange coil that fluidly connects the first branch and the second branch. Aspect 8. The heat transfer circuit of any one of aspects 5-7, wherein the plurality of valves includes a first valve and a second valve, and the two or more branches include a first branch including the first valve and a second branch including the second valve. Aspect 9. The heat transfer circuit of any one of aspects 5-8, wherein the plurality of heat exchange coils includes a first heat exchange coil, and the two or more branches include a first branch that includes the first heat exchange coil. Aspect 10. The heat transfer circuit of any one of aspects 1-9, wherein the plurality of valves includes two or more check valves. Aspect 11. The heat transfer circuit of any one of aspects 1-10, wherein the plurality of heat exchange coils of the first heat exchanger unit includes a first heat exchange coil, a flow direction of the working fluid through the first heat exchange coil changes from the first mode to the second mode. Aspect 12. The heat transfer circuit of any one of aspects 1-10, wherein the plurality of heat exchange coils of the first heat exchanger unit includes a first heat exchange coil, a flow direction of the working fluid through the first heat exchange coil is same in the first mode and the second mode. Aspect 13. The heat transfer circuit of any one of aspects 1-12, wherein the plurality of heat exchange coils of the first heat exchanger unit includes a first heat exchange coil, the working fluid and the first process fluid in the first heat exchange coil in counter-flow in the first mode. Aspect 14. A method of operating a heat transfer circuit, comprising:

operating in a first mode by:

-   -   compressing a working fluid in a compressor,     -   directing the working fluid through a first heat exchanger,         expander, and a second heat exchanger in a first direction, the         first heat exchanger including a plurality of heat exchange         coils, a process fluid flowing through the heat exchange coils         of the first heat exchanger in parallel, wherein directing the         working fluid through the first heat exchanger in the first         direction includes directing the working fluid through the         plurality of heat exchange coils of the heat exchanger in         series; and

operating in a second mode by:

-   -   compressing the working fluid in a compressor, and     -   directing the working fluid through the first heat exchanger,         the expander, and the second heat exchanger in a second         direction, wherein directing the working fluid through the first         heat exchanger in the second direction includes directing the         working fluid through the plurality of heat exchange coils of         the heat exchanger in parallel.         Aspect 15. The method of aspect 14, wherein

the first mode is a cooling mode that includes heating the first process fluid in the first heat exchanger with the working fluid and cooling the second process fluid in the second heat exchanger with the working fluid,

the second mode is a heat pump mode that includes cooling the first process fluid in the first heat exchanger with the working fluid and heating the second process fluid in the second heat exchanger with the working fluid.

Aspect 16. The method of either one of aspects 14 and 15, wherein

operating in the first mode includes positioning a reversing valve in a first position, the first position directing the working fluid after being compressed in the compressor in the first direction through the first direction through the first heat exchanger, expander, and a second heat exchanger,

operating in the second mode includes positioning the reversing valve in a second position, the second position directing the working fluid after being compressed in the compressor in the second direction through the first heat exchanger, expander, and a second heat exchanger.

The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein. 

What is claimed is:
 1. A heat transfer circuit operable in at least a first mode and a second mode, the heat transfer circuit comprising: a compressor to compress a working fluid; an expander to expand the working fluid; a first heat exchanger to exchange heat between the working fluid and a first process fluid, the first heat exchanger including a plurality of heat exchange coils, the working fluid flowing through the plurality of heat exchange coils, the first process fluid flowing through the plurality of heat exchange coils in parallel; a second heat exchanger to exchange heat between the working fluid and a second process fluid, a reversing valve configured to change a flow direction of the working fluid through the first heat exchanger; and a plurality of valves configured to direct the working fluid through the plurality of heat exchange coils of the first heat exchanger based on the flow direction of the working fluid through the first heat exchanger, wherein the working fluid flows through the plurality of heat exchange coils in series when the flow direction is a first direction, and the working fluid flows through the plurality of heat exchange coils in parallel when the flow direction is a second direction.
 2. The heat transfer circuit of claim 1, wherein the first mode is a cooling mode in which the first heat exchanger operates as a condenser that heats the first process fluid with the working fluid, the second mode is a heat pump mode in which the first heat exchanger operates as an evaporator that cools the second process fluid with the working fluid.
 3. The heat transfer circuit of claim 1, wherein the plurality of valves includes a valve blocking the working fluid in the first mode and allowing working fluid to pass through in the second mode.
 4. The heat transfer circuit of claim 3, wherein the valve blocks the working fluid in the first mode to prevent the working fluid from bypassing at least one of the plurality of heat exchange coils.
 5. The heat transfer circuit of claim 1, further comprising: a reversible main flow path for the working fluid that extends from the reversible valve through the first heat exchanger, the expander, and the second heat exchanger, and the reversible main flow path including two or more branches that direct the working fluid through the plurality of heat exchange coils.
 6. The heat transfer circuit of claim 5, wherein the reversible main flow path splits into the two or more branches between the reversible valve and the first heat exchanger, the two or more branches converging back into the reversible main flow path between the first heat exchanger and the expander.
 7. The heat transfer circuit of claim 6, wherein the two or more branches include a first branch and a second branch, the plurality of heat exchange coils including a first heat exchange coil that fluidly connects the first branch and the second branch.
 8. The heat transfer circuit of claim 5, wherein the plurality of valves including a first valve and a second valve, and the two or more branches include a first branch including the first valve and a second branch including the second valve.
 9. The heat transfer circuit of claim 5, wherein the plurality of heat exchange coils includes a first heat exchange coil, and the two or more branches include a first branch that includes the first heat exchange coil.
 10. The heat transfer circuit of claim 1, wherein the plurality of valves includes two or more check valves.
 11. The heat transfer circuit of claim 1, wherein the plurality of heat exchange coils of the first heat exchanger unit includes a first heat exchange coil, a flow direction of the working fluid through the first heat exchange coil changes from the first mode to the second mode.
 12. The heat transfer circuit of claim 1, wherein the plurality of heat exchange coils of the first heat exchanger unit includes a first heat exchange coil, a flow direction of the working fluid through the first heat exchange coil is same in the first mode and the second mode.
 13. The heat transfer circuit of claim 1, wherein the plurality of heat exchange coils of the first heat exchanger unit includes a first heat exchange coil, the working fluid and the first process fluid in the first heat exchange coil in counter-flow in the first mode.
 14. A method of operating a heat transfer circuit, comprising: operating in a first mode by: compressing a working fluid in a compressor, directing the working fluid through a first heat exchanger, expander, and a second heat exchanger in a first direction, the first heat exchanger including a plurality of heat exchange coils, a process fluid flowing through the heat exchange coils of the first heat exchanger in parallel, wherein directing the working fluid through the first heat exchanger in the first direction includes directing the working fluid through the plurality of heat exchange coils of the heat exchanger in series; and operating in a second mode by: compressing the working fluid in a compressor, and directing the working fluid through the first heat exchanger, the expander, and the second heat exchanger in a second direction, wherein directing the working fluid through the first heat exchanger in the second direction includes directing the working fluid through the plurality of heat exchange coils of the heat exchanger in parallel.
 15. The method of claim 14, wherein the first mode is a cooling mode that includes heating the first process fluid in the first heat exchanger with the working fluid and cooling the second process fluid in the second heat exchanger with the working fluid, the second mode is a heat pump mode that includes cooling the first process fluid in the first heat exchanger with the working fluid and heating the second process fluid in the second heat exchanger with the working fluid.
 16. The method of claim 14, wherein operating in the first mode includes positioning a reversing valve in a first position, the first position directing the working fluid after being compressed in the compressor in the first direction through the first direction through the first heat exchanger, expander, and a second heat exchanger, operating in the second mode includes positioning the reversing valve in a second position, the second position directing the working fluid after being compressed in the compressor in the second direction through the first heat exchanger, expander, and a second heat exchanger. 